Wireless communications system, control station, and terminal

ABSTRACT

A wireless communications system including a base station and a terminal, the wireless communications system capable of communications between terminals through a first path and communications between terminals through a second path which different the first path, the wireless communications system includes: a plurality of terminals; and the base station including to: a memory; and a processor coupled to the memory, the processor configured to process related to proximity-based communications between a plurality of terminals; obtain identifiers of the terminal and information enables determination of whether to use the second path.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.15/636,045, filed on Jun. 28, 2017, which is a continuation applicationof International Application PCT/JP2015/050690, filed on Jan. 13, 2015,and designating the U.S., the entire contents of each are incorporatedherein by reference.

FIELD

The embodiments discussed herein relate to a wireless communicationssystem, a control station, and a terminal.

BACKGROUND

Mobile communication such as Long Term Evolution (LTE) and LTE-advancedare conventionally known (for example, refer to 3GPP TS36.300 V12.1.0,March 2014; 3GPP TS36.211 V12.1.0, March 2014; 3GPP TS36.212 V12.0.0,December 2013; 3GPP TS36.213 V12.1.0, March 2014; 3GPP TS36.321 V12.0.0,December 2013; 3GPP TS36.322 V11.0.0, September 2012; 3GPP TS36.323V11.2.0, March 2013; 3GPP TS36.331 V12.0.0, December 2013; 3GPP TS36.413V12.0.0, December 2013; 3GPP TS36.423 V12.0.0, December 2013; 3GPPTR36.842 V12.0.0, December 2013; and 3GPP TS24.301 v12.6.0, September2014). Further, Proximity-based Services (ProSe) (function of directcommunication between terminals) enabling direct communication betweenterminals are being studied (for example, refer to 3GPP TR36.843V12.0.0, March 2014 and 3GPP TS33.303 v12.0.0, June 2014).

Enhancements for Infrastructure based data Communication Between Devices(eICBD) are being studied for performing communication between terminalsby a shortcut path through a base station, without passing through apacket core network such as an Evolved Packet Core (EPC) or the like(for example, refer to 3GPP TR22.807 v1.0.0, June 2014).

According to a known technique, transmission packets addressed to acommunications counterpart terminal are divided into and are transmittedas first packets that do not pass through a control apparatus thatmanages communication and second packets that pass through the controlapparatus (for example, refer to Japanese Laid-Open Patent PublicationNo. 2012-110035).

According to another known technique, when the traffic volumeconcentrates unevenly at a certain wireless base station as compared toa neighbor wireless base station, paths to the neighbor wireless basestation having low traffic are expanded for mobile devices of thewireless base station having high traffic, the paths being expandedthrough a wireless repeater (for example, refer to Japanese Laid-OpenPatent Publication No. 2000-333257).

SUMMARY

According to an aspect of an embodiment, a wireless communicationssystem includes a packet core network and a wireless access network thatincludes a base station and a terminal. The wireless communicationssystem is capable of communication between terminals through a firstpath that includes the packet core network and communication betweenterminals through a second path that does not include the packet corenetwork. The wireless communications system includes plural terminals;and a control station configured to: be capable of processing related toproximity-based communications services between the plural terminals;obtaining identifiers of the plural terminals and position informationrelated to positions of the plurality of terminals, by the processingrelated to the proximity-based communications services; and causingcommunication between the plural terminals to be executed by the secondpath, based on the identifiers of the plural terminals and the positioninformation related to the positions of the plural terminals.

The object and advantages of the invention will be realized and attainedby means of the elements and combinations particularly pointed out inthe claims.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory and arenot restrictive of the invention.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1A is a diagram depicting one example of a wireless communicationssystem according to a first embodiment;

FIG. 1B is a diagram depicting one example of signal flow in thewireless communications system depicted in FIG. 1A;

FIG. 1C is a diagram depicting a modified example of the wirelesscommunications system according to the first embodiment;

FIG. 2 is a diagram depicting one example of the wireless communicationssystem according to a second embodiment;

FIG. 3 is a diagram depicting one example of a base station;

FIG. 4 is a diagram depicting one example of a terminal;

FIG. 5 is a diagram depicting one example of hardware configuration ofthe base station;

FIG. 6 is a diagram depicting one example of hardware configuration ofthe terminal;

FIG. 7 is a diagram depicting one example of communication betweenterminals by eICBD;

FIG. 8 is a diagram depicting one example of communication betweenterminals by ProSe;

FIG. 9A is a sequence diagram (part 1) of a first example of processingin the wireless communications system;

FIG. 9B is a sequence diagram (part 2) of the first example ofprocessing in the wireless communications system;

FIG. 10 is a sequence diagram of reversion in the first example ofprocessing in the wireless communications system;

FIG. 11 is a sequence diagram of a second example of processing in thewireless communications system;

FIG. 12 is a sequence diagram of a third example of processing in thewireless communications system; and

FIG. 13 is a flowchart of an example of a process by the eNB.

DESCRIPTION OF THE INVENTION

Embodiments of a wireless communications system, a control station, anda terminal according to the present invention will be described indetail with reference to the accompanying drawings.

FIG. 1A is a diagram depicting one example of the wirelesscommunications system according to a first embodiment. FIG. 1B is adiagram depicting one example of signal flow in the wirelesscommunications system depicted in FIG. 1A. As depicted in FIGS. 1A and1B, a wireless communications system 100 according to the firstembodiment includes a packet core network 101 and a wireless accessnetwork 102. The wireless access network 102 includes a base station 110and terminals 120, 130. The packet core network 101 is a communicationsnetwork that does not include the base station 110, for example, is acommunications network higher than the base station 110.

In the wireless communications system 100, communication betweenterminals through a first path that includes the packet core network 101is possible. A second path, for example, is a shortcut path by the basestation 110. Further, in the wireless communications system 100,communications between terminals through the second path that includesno packet core network such as the packet core network 101 is alsopossible. The first path, for example, is a path passing through thebase station 110 and the packet core network 101.

The base station 110 (control station) relays communication between theterminals 120, 130 by performing wireless communication with theterminals 120, 130. For example, the base station 110 includes acommunications unit 111 and a control unit 112.

The communications unit 111 is capable of processing related toproximity-based communications services between terminals. Further, thecommunications unit 111 obtains identifiers of the terminals 120, 130and position information related to positions of the terminals 120, 130by performing the processing related to proximity-based communicationsservices. The communications unit 111 outputs the obtained positioninformation and identifiers of the terminals 120, 130 to the controlunit 112. The position information, for example, is information thatenables determination of whether the terminals 120, 130 are in proximityto each other. The position information will be described hereinafter.

Proximity-based communications services between terminals is, forexample, ProSe. The processing related to proximity-based communicationsservices between terminals is, for example, a process of accessing acommunications apparatus that provides proximity-based communicationsservices. A communications apparatus that provides proximity-basedcommunications services is, for example, a ProSe Function. For example,the communications unit 111 has a ProSe layer processing unit thus,being capable of processing related to proximity-based communicationsservices between terminals.

The control unit 112 controls communication between the terminals 120,130. For example, the control unit 112 transmits a control signal to theterminals 120, 130 and thereby controls the communication between theterminals 120, 130. The control signal transmitted to the terminals 120,130 by the control unit 112 is, for example, a response to acommunication request from the terminals 120, 130 to the base station110, information indicating a radio resource to be used by the terminals120, 130 in wireless communication with the base station 110, etc.

Based on the position information and identifiers of the terminals 120,130 output from the communications unit 111, the control unit 112further performs control to cause communication between the terminals120, 130 to be executed through the second path, which does not passthrough the packet core network 101. For example, when the terminals120, 130 are in proximity to each other based on the positioninformation of the terminals 120, 130, the control unit 112 causescommunication between the terminals 120, 130 to be executed through thesecond path, which does not pass through the packet core network 101.Further, when the terminals 120, 130 are not in proximity to each other,the control unit 112 causes communication between the terminals 120, 130to be execute through the first path, which passes through the packetcore network 101.

The terminals 120, 130 are mobile stations that wirelessly communicatewith the base station 110. For example, the terminal 120 includes acommunications unit 121 and a control unit 122. The communications unit121 is capable of communicating with other terminals (for example, theterminal 130). The control unit 122 controls communication by thecommunications unit 121 based on a control signal transmitted from thebase station 110. Although configuration of the terminal 120 isdescribed, configuration of the terminal 130 is identical to that of theterminal 120.

Thus, according to the first embodiment, processing related toproximity-based communications services between terminals is implementedby the base station 110 and the base station 110 is capable of using theprocessing related to proximity-based communications services andascertaining proximity between terminals. As a result, shortcutcommunication through a base station is executed between terminals thatare in proximity to each other (for example, the terminals 120, 130)whereby the amount of traffic on the packet core network 101 can bereduced.

FIG. 1C is a diagram depicting a modified example of the wirelesscommunications system according to the first embodiment. In FIG. 1C,portions identical to those depicted in FIGS. 1A and 1B are given thesame reference characters used in FIGS. 1A and 1B, and descriptionthereof is omitted hereinafter. As depicted in FIG. 1C, in the firstembodiment, the wireless access network 102 may include the base station110 and a base station 140, and the terminal 130 may be connected to thebase station 140. The base station 140 is connected to the base station110 by, for example, an X1 interface or the like.

In this case, the first path between the terminals 120, 130 describedabove is a path that passes through the base station 110, the packetcore network 101, and the base station 140. Further, the second pathbetween the terminals 120, 130 described above is a path passing throughthe base station 110 and the base station 140. In the second path,communication is performed between the base station 110 and the basestation 140 directly or through another base station, etc., withoutpassing through the packet core network 101.

Thus, even when terminals are connected to different base stations, thebase station 110 is capable of using processing related toproximity-based communications services and ascertaining proximitybetween terminals. As a result, shortcut communication through multiplebase stations (for example, the base stations 110, 140) is executedbetween terminals that are in proximity to each other (for example, theterminals 120, 130) and a reduction of traffic on the packet corenetwork 101 is possible.

The position information is, for example, information that enablesdetermination of whether the distance between the positions of theterminals 120, 130 is at least a predetermined distance. Informationthat enables determination of whether the distance between the positionsof the terminals 120, 130 is at least the predetermined distance is, forexample, information that can specify the distance between the positionsof the terminals 120, 130. Alternatively, information that enablesdetermination of whether the distance between the positions of theterminals 120, 130 is at least the predetermined distance may beinformation that can indicate whether the distance between the positionsof the terminals 120, 130 is at least the predetermined distance.Information that can specify the distance between the positions of theterminals 120, 130 may be, for example, information that indicates thepositions (for example, position coordinates) of the terminals 120, 130,information that can indicate the distance (for example, directdistance) between the positions of the terminals 120, 130, etc.

For example, when the position information is information that canspecify the distance between the positions of the terminals 120, 130,the control unit 112 determines from the position information, thedistance between the positions of the terminals 120, 130. When thedetermined distance is the predetermined distance or more, the controlunit 112 causes communication between the terminals 120, 130 to beexecuted through the first path, which passes through the packet corenetwork 101. Further, when the determined distance is less than thepredetermined distance, the control unit 112 causes communicationbetween the terminals 120, 130 to be executed through the second path,which does not pass through the packet core network 101.

Nonetheless, the position information is not limited hereto and may beany type of information related to the positions of the terminals 120,130, provided that the position information, for example, enablesdetermination of whether to use the second path, which does not passthrough the packet core network 101.

For example, the position information may be information that enablesdetermination of whether the areas in which terminals 120, 130 arelocated are the same area or enables determination of whether the areasin which the terminals 120, 130 are located are areas in proximity toeach other. Information that enables determination of whether the areasin which the terminals 120, 130 are located are the same area ordetermination of whether the areas in which the terminals 120, 130 arelocated are areas that are in proximity to each other is, for example,information that indicates the areas in which the terminals 120, 130 arelocated. Alternatively, the information that enables determination ofwhether areas in which the terminals 120, 130 are located are the samearea or determination of whether the areas in which the terminals 120,130 are located are areas that are in proximity to each other may beinformation that indicates whether the areas in which the terminals 120,130 are located are the same area or that indicates whether the areas inwhich the terminals 120, 130 are located are areas that are in proximityto each other.

For example, when the position information is information that indicatesthe areas in which the terminals 120, 130 are located, the control unit112 identifies from the position information, the areas in which theterminals 120, 130 are located. When the identified areas are the samearea or areas that are in proximity to each other, the control unit 112causes communication between the terminals 120, 130 to be executedthrough the second path, which does not pass through the packet corenetwork 101. Further, when the identified areas are not the same area orare not areas that are in proximity to each other, the control unit 112causes communication between the terminals 120, 130 to be executedthrough the first path, which passes through the packet core network101. Whether the identified areas are areas in proximity to each other,for example, can be determined using information that specifies areasthat are in proximity to each other. Information that specifies areasthat are in proximity to each other may be information that is stored inthe memory of the base station 110 or may be information that isreceived by the base station 110 from an external apparatus.

Further, the position information may be information that enablesdetermination of whether the base stations to which the terminals 120,130 are connected are the same base station (for example, the basestation 110) or that enables determination of whether the base stationsto which the terminals 120, 130 are connected are in proximity to eachother. Information that enables determination of whether the basestations to which the terminals 120, 130 are connected are the same basestation or that enables determination of whether the base stations arein proximity to each other is information that indicates, for example,the base stations to which the terminals 120, 130 are connected.Alternatively, information that enables determination of whether thebase stations to which the terminals 120, 130 are connected are the samebase station or that enables determination of whether the base stationsare in proximity to each other may be information that indicates whetherthe base stations to which the terminals 120, 130 are connected are thesame base station or that indicates whether the base stations are basestations that are in proximity to each other.

For example, when the position information is information that indicatesthe base stations to which the terminals 120, 130 are connected, thecontrol unit 112 identifies from the position information, the basestations to which the terminals 120, 130 are connected. When theidentified base stations are the same base station or are base stationsthat are in proximity to each other, the control unit 112 causescommunication between the terminals 120, 130 to be executed through thesecond path, which does not pass through the packet core network 101.Further, when the identified base stations are not the same base stationor are not in proximity to each other, the control unit 112 causescommunication between the terminals 120, 130 to be executed through thefirst path that passes through the packet core network 101. Whether theidentified base stations are base stations in proximity to each other,for example, can be determined using information that specifies basestations that are in proximity to each other. Information that specifiesbase stations that are in proximity to each other may be informationstored in the memory of the base station 110 or may be informationreceived by the base station 110 from an external apparatus.

Further, the position information may be information that enablesdetermination of whether cells to which the terminals 120, 130 areconnected are the same cell (for example, a cell of the base station110) or determination of whether the cells to which the terminals 120,130 are connected are cells that are in proximity to each other.Information that enables determination of whether cells to which theterminals 120, 130 are connected are the same cell or determination ofwhether the cells to which the terminals 120, 130 are connected arecells that are in proximity to each other is, for example, informationthat indicates the cells to which the terminals 120, 130 are connected.Alternatively, information that enables determination of whether thecells to which the terminals 120, 130 are connected are the same cell ordetermination of whether the cells to which the terminals 120, 130 areconnected are cells that are in proximity to each other may beinformation that indicates whether the cells to which the terminals 120,130 are connected are the same cell or that indicates whether the cellsare cells that are in proximity to each other.

For example, when the position information is information that indicatesthe cells to which the terminals 120, 130 are connected, the controlunit 112 identifies from the position information, the cells to whichthe terminals 120, 130 are connected. When the identified cells are thesame cell or are cells that are in proximity to each other, the controlunit 112 causes communication between the terminals 120, 130 to beexecuted through the second path, which does not pass through the packetcore network 101. Further, when the identified cells are not the samecell or are not cells that are in proximity to each other, the controlunit 112 causes communication between the terminals 120, 130 to beexecuted through the first path, which passes through the packet corenetwork 101. Whether the identified cells are cells that are inproximity to each other, for example, can be determined usinginformation specifying cells that are in proximity to each other.Information specifying cells that are in proximity to each other may beinformation stored on the memory of the base station 110 or may bereceived by the base station 110 from an external apparatus.

Further, the position information is information that enablesdetermination of whether the distance between the positions of the basestations to which the terminals 120, 130 are connected is at least apredetermined distance. Information that enables determination ofwhether the distance between the positions of the base stations to whichthe terminals 120, 130 are connected is at least the predetermineddistance, for example, may be information that can specify the distancebetween the positions of the base stations or information that canindicate whether the distance between the positions of the base stationsis at least the predetermined distance. Information that can specify thedistance between the positions of the base stations, for example, may beinformation that indicates the positions (for example, positioncoordinates) of the base stations, information that indicates thedistance (for example, direct distance) between the positions of thebase stations, etc.

For example, when the position information is information that canspecify the distance between the positions of the base stations to whichthe terminals 120, 130 are connected, the control unit 112 determinesfrom the position information, the distance between the positions of thebase stations to which the terminals 120, 130 are connected. When thedetermined distance is the predetermined distance or more, the controlunit 112 causes communication between the terminals 120, 130 to beexecuted through the first path, which passes through the packet corenetwork 101. Further, when the determined distance is less than thepredetermined distance, the control unit 112 causes communicationbetween the terminals 120, 130 to be executed through the second path,which does not pass through the packet core network 101.

Further, the position information is information that enablesdetermination of whether a relay count (for example, a count of the X1interfaces) between base stations to which the terminals 120, 130 areconnected is at least a predetermined count. Information that enablesdetermination of whether a relay count between base stations to whichthe terminals 120, 130 are connected is at least the predeterminedcount, for example, may be information that can specify the relay countbetween the base stations, information that indicates whether the relaycount between the base stations is at least the predetermined count,etc.

For example, when the position information is information that canspecify the relay count between the base stations to which the terminals120, 130 are connected, the control unit 112 obtains from the positioninformation, the relay count between the base stations to which theterminals 120, 130 are connected. When the obtained relay count is thepredetermined count or more, the control unit 112 causes communicationbetween the terminals 120, 130 to be executed through the first path,which passes through the packet core network 101. Further, when theobtained relay count is less than the predetermined count, the controlunit 112 causes communication between the terminals 120, 130 to beexecuted through the second path, which does not pass through the packetcore network 101.

The position information of these various types is information that byproviding the base station 110 with a processing unit related toproximity-based communications services, can be obtained by the basestation 110 from a communications apparatus that provides, for example,proximity-based communications services.

Criteria for determining whether to use the second path, which does notpass through the packet core network 101, for example, can be setaccording to whether the amount of delay of communication between theterminals 120, 130 when the second path that does not pass through thepacket core network 101 is used is less than a predetermined amount. Inother words, the predetermined distances, the information indicatingareas that are in proximity to each other, the information indicatingbase stations that are in proximity to each other, the informationindicating cells that are in proximity to each other, etc. describedabove, for example, can be set based on the amount of delay of thecommunication between the terminals 120, 130 when the second path isused.

The node that is to finally realize the shortcut path can be determinedby a node of the packet core network. For example, in the packet corenetwork 101, an MME 221 (control station) that manages bearers that aretransmission paths is a starting point and starts the shortcutcommunication.

Since the MME 221 and a ProSe function 224 are connected by S6a and PC4ainterfaces through a HSS 223, the MME 221 is capable of obtaining theposition information ascertained by the ProSe function and based on theposition information, is capable of determining whether to implement theshortcut communication through a base station. When the shortcutcommunication is to be implemented, communication path configuration,bearer configuration, etc. is performed. Alternatively, since the MME221 and eNBs are connected by an S1-C interface, the MME 221 is capableof obtaining the position information ascertained by the base stationand based on the position information, determining whether shortcutcommunication through a base station is to be implemented. When shortcutcommunication is to be implemented, communication path configuration,bearer configuration, etc. is performed.

FIG. 2 is a diagram depicting one example of the wireless communicationssystem according to a second embodiment. As depicted in FIG. 2, awireless communications system 200 according to the second embodimentincludes a wireless access network 210 and an EPC 220. The wirelessaccess network 210 is a communications network on which wirelesscommunication is performed. For example, the wireless access network 210includes User Equipment ((UEs): user terminals) 201, 202, and evolvedNodes B (eNBs) 211 to 213.

The EPC 220 is a packet core network in the wireless communicationssystem 200. For example, the EPC 220 includes the MME 221 (MobilityManagement Entity), a gateway 222 (S/PGW), the HSS 223 (Home SubscriberServer), and the ProSe function 224.

The UEs 201, 202 each performs wireless communication with at least oneof the eNBs 211 to 213 and thus, is capable of wireless communicationwith the EPC 220 via at least one of the eNBs 211 to 213. Further, theUEs 201, 202 are capable of communicating with each other via at leastone of the eNBs 211 to 213.

The eNBs 211 to 213 are each a base station that performs wirelesscommunication with the UEs 201, 202 to thereby relay communicationbetween the EPC 220 and the UEs 201, 202. Further, the eNBs 211 to 213are each connected to the MME 221 via an S1 interface. Further, the eNBs211 to 213 are each connected to the ProSe function 224 via a PC3interface.

The MME 221 accommodates the eNBs 211 to 213 and performs a Controlplane (C-plane) process for network control.

The gateway 222 is a gateway in the EPC 220. For example, the gateway222 includes a Serving Gateway (S-GW) that manages a User-plane of userdata, a Packet data network Gateway (P-GW) for connecting to an externalnetwork, a corporate intranet, etc.

The HSS 223 is a server that manages service control and subscriberdata.

The ProSe function 224 is a communications apparatus that performs aprocess related to proximity-based communications services (ProSe) atthe UEs 201, 202. For example, the ProSe function 224 is capable ofobtaining position information related to the positions of the UEs 201,202 in order to provide ProSe.

For example, the ProSe function 224 is capable of obtaining positioninformation based on report information from the UEs 201, 202. Thereport information, for example, is information that indicatesmeasurement results of position coordinates of the UEs 201, 202,obtained by a Global Positioning System (GPS) unit in the UEs 201, 202.Alternatively, the report information may be identification informationof the cell or base station to which the UEs 201, 202 are connected. TheProSe function 224 may be an independent communications apparatus or maybe provided in another communications apparatus.

Further, the eNB 211 and the eNB 212 can implement a ProSe protocol. TheeNB 213 can also implement the ProSe protocol. The ProSe protocol may beconfigured as, for example, a higher layer of a Radio Resource Control(RRC) protocol, a layer 2 (L2) protocol, and a physical layer (PHY)protocol.

As a result, the eNBs 211 to 213 are able to access the ProSe protocolof the ProSe function 224. In this access, for example, use of the PC3interface is possible. As a result, the eNBs 211 to 213 are capable ofusing the ProSe protocol and obtaining from the ProSe function 224,position information related to the positions of the UEs 201, 202.

The packet core network 101 depicted in FIGS. 1A to 1C, for example, canbe implemented by the EPC 220. The wireless access network 102 depictedin FIGS. 1A to 1C, for example, can be implemented by the wirelessaccess network 210. The base stations 110, 140 depicted in FIGS. 1A to1C, for example, can be implemented by the eNBs 211 to 213. Theterminals 120, 130 depicted in FIGS. 1A to 1C, for example, can beimplemented by the UEs 201, 202.

FIG. 3 is a diagram depicting one example of the base station. The eNBs211 to 213 can each be implemented by, for example, a base station 300depicted in FIG. 3. As depicted in FIG. 3, the base station 300includes, for example, a wireless communications unit 310, a controlunit 320, a storage unit 330, and a communications unit 340. Thewireless communications unit 310 includes a wireless transmitting unit311 and a wireless receiving unit 312. These configurations areconnected to enable unidirectional or bidirectional input and output ofdata and signals.

The wireless transmitting unit 311 transmits user data and a controlsignal by wireless communication, via an antenna. A wireless signaltransmitted by the wireless transmitting unit 311 can include arbitraryuser data, control information, etc. (that has been encoded, modulated,etc.). The wireless receiving unit 312 receives user data and controlsignals by wireless communication, via an antenna. A wireless signalreceived by the wireless receiving unit 312 can include arbitrary userdata, a control signal, etc. (that has been encoded, modulated, etc.). Acommon antenna may be used for transmission and reception.

The control unit 320 outputs to the wireless transmitting unit 311, userdata and control signals that are to be transmitted to another wirelessstation. Further, the control unit 320 obtains user data and controlsignals received by the wireless receiving unit 312. The control unit320 performs the input and output of programs, control information, userdata, etc. with respect to the storage unit 330 described hereinafter.Further, the control unit 320 performs with respect to thecommunications unit 340 described hereinafter, the input and output ofcontrol signals and user data transmitted to and received from anothercommunications apparatus, etc. The control unit 320 additionallyperforms various types of control in the base station 300.

The storage unit 330 stores various types of information such as userdata, control information, programs, etc. The communications unit 340,for example, by a wired signal, transmits to and receives from anothercommunications apparatus, user data and control signals.

The communications unit 111 of the base station 110 depicted in FIGS. 1Ato 1C, for example, can be implemented by the control unit 320 and thecommunications unit 340. The control unit 112 of the base station 110depicted in FIGS. 1A to 1C, for example, can be implemented by thewireless communications unit 310, the control unit 320, and thecommunications unit 340.

FIG. 4 is a diagram depicting one example of a terminal. The UEs 201,202, for example, can be implemented by a terminal 400 depicted in FIG.4. The terminal 400 includes a wireless communications unit 410, acontrol unit 420, and a storage unit 430. The wireless communicationsunit 410 includes a wireless transmitting unit 411 and a wirelessreceiving unit 412. These configurations are connected to enableunidirectional or bidirectional input and output of data and signals.

The wireless transmitting unit 411 transmits user data and a controlsignal by wireless communication, via an antenna. A wireless signaltransmitted by the wireless transmitting unit 411 can include arbitraryuser data, control information, etc. (that has been encoded, modulated,etc.). The wireless receiving unit 412 receives user data and controlsignals by wireless communication, via an antenna. A wireless signalreceived by the wireless receiving unit 412 can include arbitrary userdata, a control signal, etc. (that has been encoded, modulated, etc.). Acommon antenna may be used for transmission and reception.

The control unit 420 outputs to the wireless transmitting unit 411, userdata and control signals that are to be transmitted to another wirelessstation. Further, the control unit 420 obtains user data and controlsignals received by the wireless receiving unit 412. The control unit420 performs the input and output of programs, control information, userdata, etc. with respect to the storage unit 430 described hereinafter.Further, the control unit 420 performs with respect to a communicationsunit described hereinafter, the input and output of control signals anduser data transmitted to and received from another communicationsapparatus, etc. The control unit 420 additionally performs various typesof control in the terminal 400.

The storage unit 430 stores various types of information such as userdata, control information, programs, etc.

The communications unit 121 of the terminal 120 depicted in FIGS. 1A to1C, for example, can be implemented by the wireless communications unit410. The control unit 122 of the terminal 120 depicted in FIGS. 1A to1C, for example, can be implemented by the wireless communications unit410 and the control unit 420.

FIG. 5 is a diagram depicting one example of hardware configuration ofthe base station. The base station 300 depicted in FIG. 3, for example,can be implemented by a base station 500 depicted in FIG. 5. The basestation 500 includes an antenna 511, an RF circuit 512, a processor 513,a memory 514, and a network IF 515. These components, for example, areconnected via a bus so as to enable the input and output of varioussignals and data.

The antenna 511 includes a transmission antenna that transmits wirelesssignals and a reception antenna that receives wireless signals. Further,the antenna 511 may be a common antenna used for both transmitting andreceiving wireless signals. The RF circuit 512 performs a RadioFrequency ((RF): high frequency) process for signals received by theantenna 511 and signals transmitted by the antenna 511. The RF process,for example, includes frequency conversion for a baseband width and anRF band.

The processor 513, for example, is a central processing unit (CPU), adigital signal processor (DSP), or the like. Further, the processor 513can be implemented by a digital electronic circuit such as anApplication Specific Integrated Circuit (ASIC), a Field ProgrammableGate Array (FPGA), a Large Scale Integration ((LSI): large-scaleintegrated circuit), or the like.

The memory 514, for example, can be implemented by flash memory,read-only memory (ROM), random access memory (RAM) such as SynchronousDynamic Random Access Memory (SDRAM), etc. The memory 514 stores, forexample, user data, control information, programs, and the like.

The network IF 515 is, for example, a communications interface thatperforms wired communication with a network. The network IF 515 mayinclude, for example, an Xn interface for performing wired communicationwith a base station.

The wireless communications unit 310 depicted in FIG. 3, for example,can be implemented by the RF circuit 512, or by the antenna 511 and theRF circuit 512. The control unit 320 depicted in FIG. 3, for example,can be implemented by the processor 513 and the memory 514. The storageunit 330 depicted in FIG. 3, for example, can be implemented by thememory 514. The communications unit 340 depicted in FIG. 3, for example,can be implemented by the network IF 515.

FIG. 6 is a diagram depicting one example of hardware configuration ofthe terminal. The terminal 400, for example, can be implemented by aterminal 600 depicted in FIG. 6. The terminal 600 includes, for example,an antenna 611, an RF circuit 612, a processor 613, and a memory 614.The components, for example, are connected via a bus so as to enable theinput and output of various signals and data.

The antenna 611 includes a transmission antenna that transmits wirelesssignals and a reception antenna that receives wireless signals. Further,the antenna 611 may be a common antenna used for both transmitting andreceiving wireless signals. The RF circuit 612 performs an RF processfor signals received by the antenna 611 and for signals transmitted bythe antenna 611. The RF process, for example, includes frequencyconversion for a baseband width and an RF band.

The processor 613, for example, is a CPU, a DSP, or the like. Further,the processor 613 may be implemented by a digital electronic circuitsuch as an ASIC, a FPGA, an LSI, or the like.

The memory 614, for example, can be implemented by flash memory, ROM,RAM such as SDRAM, etc. The memory 614 stores, for example, user data,control information, programs, and the like.

The wireless communications unit 410 depicted in FIG. 4, for example,can be implemented by the RF circuit 612, or by the antenna 611 and theRF circuit 612. The control unit 420 depicted in FIG. 4, for example,can be implemented by the processor 613 and the memory 614. The storageunit 430 depicted in FIG. 4, for example, can be implemented by thememory 614.

FIG. 7 is a diagram depicting one example of communication betweenterminals by eICBD. In FIG. 7, portions depicted in FIG. 2 are given thesame reference characters used in FIG. 2, and description thereof isomitted hereinafter. UEs 201 to 203 are UEs in cellular coverage of theeNB 211. UE 204 is a UE in cellular coverage of an eNB (for example, theeNB 212 depicted in FIG. 2) different from the eNB 211.

In the example depicted in FIG. 7, the UE 201 and the UE 202 are on ashortcut path by the eNB 211 and communicate with each other through apath that does not pass through the EPC 220. In other words, the UE 201and the UE 202 each performs wireless communication with the eNB 211 andthereby communicates via the eNB 211.

As a result, since the UE 201 and the UE 202 are capable ofcommunicating with each other through a path that does not pass throughthe EPC 220, a reduction of the amount of traffic flow on the EPC 220 ispossible. Further, in the example depicted in FIG. 7, although anexample of eICBD through one eNB (the eNB 211) is described, eICBDthrough plural eNBs can be performed. In this case, in the path betweenthe plural eNBs, for example, an X2 can be used.

FIG. 8 is a diagram depicting one example of communication betweenterminals by ProSe. In FIG. 8, portions identical to those depicted inFIG. 7 are given the same reference characters used in FIG. 7 anddescription thereof is omitted hereinafter. In the example depicted inFIG. 8, the UE 201 and the UE 202 in cellular coverage of the eNB 211are performing direct wireless communication with each other under thecontrol of the eNB 211.

Further, in the example depicted in FIG. 8, the UE 203 in cellularcoverage of the eNB 211 and the UE 204 in cellular coverage of an eNB(for example, the eNB 212 depicted in FIG. 2) different from the eNB 211are performing direct wireless communication with each other under thecontrol of the eNB 211.

For example, the eNB 211 has the ProSe function depicted in FIG. 8 andis capable of using the ProSe function to obtain the positioninformation of the UEs. Based on the obtained position information, theeNB 211 is capable of determining whether terminals are in proximity toeach other and causing communication between terminals in proximity toeach other to be executed according to the eICBD depicted in FIG. 7.

FIG. 9A is a sequence diagram (part 1) of a first example of processingin the wireless communications system. In FIG. 9A, a case will bedescribed in which the UEs 201, 202 and the eNB 211 are connected, anddata transmission from the UE 201 to the UE 202 is performed.

First, the UE 201 (UE_1) and the UE 202 (UE_2) perform a serviceauthorization process with the ProSe function 224 (step S901). Theoperation at step S901, for example, is performed by the UE 201 and theUE 202 according to the ProSe protocol, via the eNB 211.

Next, the UE 201 transmits a UE registration request (UE RegistrationRequest) to the ProSe function 224 (step S902). The UE registrationrequest transmitted at step S902 includes, for example, theInternational Mobile Subscriber Identity (IMSI) “IMSI_1” of the UE 201.The operation at step S902, for example, is performed by the UE 201according to the ProSe protocol, via the eNB 211.

Next, the ProSe function 224 performs an authorization process(Authorization) with the HSS 223, for the communication of the UE 201(step S903). Next, the ProSe function 224 transmits to the UE 201, a UEregistration response (UE Registration Response) to the UE registrationrequest transmitted at step S902 (step S904). The UE registrationresponse transmitted at step S904, for example, includes the EPC ProSeUser ID (EPUID) “EPUID_1” given to the UE 201. The UE registrationresponse transmitted at step S904, for example, is received by andprocessed at the UE 201 according to the ProSe protocol. Furthermore,the operation at step S904 is performed via the eNB 211.

Next, the UE 202 transmits a UE registration request to the ProSefunction 224 (step S905). The UE registration request transmitted atstep S905 includes, for example, IMSI_2, which is the IMSI of the UE202. The operation at step S905, for example, is performed by the UE 202according to the ProSe protocol. Furthermore, the operation at step S905is performed via the eNB 211.

Next, the ProSe function 224 performs an authorization process with theHSS 223, for communication of the UE 202 (step S906). Next, the ProSefunction 224 transmits to the UE 202, a UE registration response to theUE registration request transmitted at step S905 (step S907). The UEregistration response transmitted at step S907 includes, for example,the EPUID “EPUID_2” given to the UE 202. The UE registration responsetransmitted at step S907, for example, is received and processed by theUE 202 according to the ProSe protocol. Furthermore, the operation atstep S907 is performed via the eNB 211.

Next, the UE 201 transmits a Non Access Stratum (NAS) attach and NASservice request (NAS Service Attach/Request) to the MME 221 (step S908).The NAS service request transmitted at step S908 includes a RoutingOptimization Preference (ROP) requesting path optimization by usingshortcut through the base station. The NAS service request transmittedat step S908 further includes identification information of the UE 201such as IMSI_1, EPUID_1, etc. The operation at step S908, for example,is performed by the UE 201 and the MME 221 according to a NAS protocol.Furthermore, the operation at step S908 is performed via the eNB 211.

Next, the MME 221 performs an authorization process with the HSS 223,for communication using the ROP of the UE 201 (step S909). The operationat step S909 is performed by the MME 221 according to the NAS protocol.

Next, the UE 202 transmits a NAS attach and NAS service request to theMME 221 (step S910). The NAS service request transmitted at step S910includes an ROP requesting path optimization by using shortcut throughthe base station. The NAS service request transmitted at step S910further includes identification information of the UE 202 such asIMSI_2, EPUID_2, etc. The operation at step S910, for example, isperformed by the UE 202 and the MME 221 according to the NAS protocol.Furthermore, the operation at step S910 is performed via the eNB 211.

Next, the MME 221 performs an authorization process with the HSS 223,for communication using the ROP of the UE 202 (step S911). The operationat step S911 is performed by the MME 221 according to the NAS protocol.

Next, the MME 221 transmits to the ProSe function 224, an ROP requestingpath optimization through the base station for the UEs 201, 202 (stepS912). The operation at step S912 is performed by the MME 221 accordingto the NAS protocol and based on the NAS service requests transmitted atsteps S908, S910 by the UEs 201, 202. The ROP transmitted at step S912includes identification information of the UEs 201, 202 such as IMSI_1,IMSI_2, or EPUID_1, EPUID_2, etc.

Next, the ProSe function 224 performs a proximity check whether the UEs201, 202 are in proximity to each other (step S913). In the proximitycheck, for example, Location Service (LCS) information, the ProSe UE IDs(EPUID_1, EPUID_2), and the IMSIs (IMSI_1, IMSI_2) of the UEs 201, 202are used. The LCS information of the UEs 201, 202 is information thatindicates the geographical location of the UEs 201, 202.

The ProSe function 224 supports the ProSe of the UEs 201, 202 and thus,is capable of obtaining the LCS information of the UEs 201, 202. TheProSe function 224, for example, may obtain the LCS information of theUEs 201, 202 in advance (for example, periodically). Alternatively, theProSe function 224 may obtain the LCS information of the UEs 201, 202after receiving the ROP at step S912.

The LCS information of the UEs 201, 202 is, for example, informationindicating positional coordinates of the UEs 201, 202. Alternatively,the LCS information of the UEs 201, 202 may be information indicatingidentification information of the area in which the UEs 201, 202 arelocated. Alternatively, the LCS information of the UEs 201, 202 may bethe identification information of the base station (for example, the eNB211) to which the UEs 201, 202 are connected. Alternatively, the LCSinformation of the UEs 201, 202 may be the identification information ofthe cell to which the UEs 201, 202 are connected (for example, the cellof the eNB 211).

Further, the LCS information of the UEs 201, 202 is, for example,information reported by the UEs 201, 202, to a communications apparatus(for example, the ProSe function 224) of the EPC 220, via the basestation (for example, the eNB 211) to which the UEs 201, 202 areconnected.

In the example depicted in FIG. 9A, whether the UEs 201, 202 are inproximity to each other is determined by a proximity check. In thiscase, the ProSe function 224 transmits to the eNB 211, a proximity alert(Proximity Alert) indicating that the UEs 201, 202 are in proximity toeach other (OK) (step S914). The proximity alert includes identificationinformation (for example, IMSI_1, IMSI_2 or EPUID_1, EPUID_2) of the UEs201, 202.

The proximity alert transmitted at step S914, for example, is receivedand processed by the eNB 211 according to the ProSe protocol. As aresult, the eNB 211 is capable of obtaining from the ProSe function 224,identifiers of the UEs 201, 202 and position information related to thepositions of the UEs 201, 202.

Next, the eNB 211 outputs an ROP from a ProSe protocol processing unitto a U-Plane protocol processing unit (step S915). The eNB 211 optimizesthe route of the communication of the UEs 201, 202 (step S916). Theoperation at step S916 is performed by the eNB 211 according to theProSe protocol and the U-Plane protocol.

FIG. 9B is a sequence diagram (part 2) of the first example ofprocessing in the wireless communications system. The route optimizationdepicted in FIG. 9B, for example, is the route optimization at step S916depicted in FIG. 9A. In the example depicted in FIG. 9B, thecommunication path between the UEs 201, 202 is assumed to be configuredto be a shortcut communication path through the eNB 211 followed by/as aconsequence of route optimization.

First, according to the U-Plane protocol, the UE 201 transmits to theeNB 211, user data (User Plane Data) to be transmitted to the UE 202.Next, according to the U-Plane protocol, the eNB 211 performs a routingprocess using the optimized route and transmits to the UE 202, the userdata transmitted from the UE 201.

The routing, as described above, for example, can be implemented bycontrolling the configuration of the communication paths, bearers, etc.by the MME 221. Alternatively, both base stations can store a tableassociating the identifier (address) of the counterpart base station towhich communication is being performed with the ProSe ID of the mobilestation and implements the routing according to the correspondenceindicated by the table.

Thus, in the examples depicted in FIGS. 9A and 9B, the eNB 211 causescommunication between the UEs 201, 202 to be executed through a paththat does not pass through the EPC 220 whereby a reduction of traffic onthe EPC 220 is possible.

In the examples depicted in FIGS. 9A and 9B, although description hasbeen given for a case in which the ProSe function 224 determines thatthe UEs 201, 202 are in proximity to each other, in some instances, theProSe function 224 may determine that the UEs 201, 202 are not inproximity to each other.

In these instances, the ProSe function 224 transmits to the eNB 211, aproximity alert indicating that the UEs 201, 202 are not in proximity toeach other (NG). In this case, communication through a path passingthrough the eNB 211 and the EPC 220 (for example, the gateway 222) isstarted between the UEs 201, 202.

FIG. 10 is a sequence diagram of reversion in the first example ofprocessing in the wireless communications system. In FIG. 10, portionsidentical to those depicted in FIG. 9A are given the same referencecharacters used in FIG. 9A and description thereof is omittedhereinafter.

In a case where the UEs 201, 202 have been determined to be in proximityto each other by the proximity check at step S913, the ProSe function224 may continually (for example, periodically) perform the proximitycheck thereafter (steps S1001 to S1003). In the example depicted in FIG.10, the UEs 201, 202 are assumed to be in proximity of each other (OK)as determined by the proximity checks at steps S1001, S1002. Further,the UEs 201, 202 are assumed to not be in proximity to each other (NG)as determined by the proximity check at step S1003.

In this case, the ProSe function 224 transmits to the eNB 211, aproximity alert indicating that the UEs 201, 202 are not in proximity toeach other (NG) (step S1004). In this case, the communication throughthe path not passing through the EPC 220 depicted in FIG. 9B issuspended between the UEs 201, 202 and communication through the eNB 211and the EPC 220 is started.

The ProSe function 224 may transmit a proximity alert (OK) to the eNB211 each time the UEs 201, 202 are determined to be in proximity to eachother (OK) by the proximity checks at steps S1001, S1002.

FIG. 11 is a sequence diagram of a second example of processing in thewireless communications system. In FIG. 11, a case will be described inwhich the UEs 201, 202 and the eNB 211 are connected, and voicecommunication (telephone calling) between the UEs 201, 202 is performed.Operations at steps S1101 to S1107 depicted in FIG. 11 are identical tothe operations at steps S901 to S907 depicted in FIG. 9A.

After step S1107, the UE 201 transmits a NAS attach (NAS Attach) to theMME 221 (step S1108). The operation at step S1108, for example, isperformed by the UE 201 and the MME 221 according to the NAS protocol.Furthermore, the operation at step S1108 is performed via the eNB 211.

The UE 202 also transmits a NAS attached to the MME 221 (step S1109).The operation at step S1109, for example, is performed by the UE 202 andthe MME 221 according to the NAS protocol. Furthermore, the operation atstep S1109 is performed via the eNB 211.

Next, the UE 201 transmits to the MME 221, a NAS service request (NASService Request) requesting an outgoing call to the UE 202 (step S1110).The NAS service request transmitted at step S1110 includes an ROPrequesting path optimization by using shortcut through the base station.Further, the NAS service request transmitted at step S1110 includesidentification information of the UE 201 such as IMSI_1, EPUID_1, etc.The operation at step S1110, for example, is performed by the UE 201 andthe MME 221 according to the NAS protocol. Furthermore, the operation atstep S1110 is performed via the eNB 211.

Next, the MME 221 performs an authorization process with the HSS 223,for voice communication between the UEs 201, 202, using the ROP (stepS1111). The operation at step S1111 is performed by the MME 221according to the NAS protocol.

Next, the MME 221 transmits to the ProSe function 224, an ROP requestingpath optimization for the UEs 201, 202 by using shortcut through thebase station (step S1112). The operation at step S1112 is performed bythe MME 221 according to the NAS protocol and based on the NAS servicerequest transmitted at step S1110 by the UE 201. The ROP transmitted atstep S1112 includes identification information of the UEs 201, 202 suchas IMSI_1, IMSI_2, or EPUID_1, EPUID_2, or the like.

Next, the ProSe function 224 performs a proximity check whether the UEs201, 202 are in proximity to each other (step S1113). The proximitycheck at step S1113, for example, is identical to the proximity check atstep S913 depicted in FIG. 9A. In the example depicted in FIG. 11, theUEs 201, 202 are assumed to be in proximity to each other as determinedby the proximity check. In this case, the ProSe function 224 transmitsto the MME 221, an ACK (ACKnowledgement) indicating that the UEs 201,202 are in proximity to each other (step S1114). The ACK transmitted atstep S1114, for example, is received and processed by the MME 221according to the NAS protocol.

Next, the MME 221 transmits to the eNB 211, a page (Paging) thatincludes an ACK indicating that the UEs 201, 202 are in proximity toeach other (step S1115). The page transmitted at step S1115 includesidentification information of the UEs 201, 202 (for example, IMSI_1,IMSI_2, or EPUID_1, EPUID_2). As a result, the eNB 211 is capable ofobtaining from the ProSe function 224, identifiers of the UEs 201, 202and position information related to the positions of the UEs 201, 202,via the MME 221.

Next, the eNB 211 transmits to the UE 202, the page transmitted at stepS1115 (step S1116) and thereby calls the UE 202. The operation at stepS1116 is performed by the eNB 211 and the UE 202 according to the S1Application Protocol (S1AP).

Next, the UE 202 transmits to the MME 221, a NAS service requestrequesting voice communication with the UE 201 (step S1117). Theoperation at step S1117, for example, is performed by the UE 202according to the NAS protocol. Furthermore, the operation at step S1117,for example, is performed via the eNB 211.

Thus, as depicted in FIG. 9B, for example, communication through ashortcut path via the eNB 211 starts between the UEs 201, 202. However,in the example depicted in FIG. 11, since voice communication isperformed between the UEs 201, 202, the communication between the UEs201, 202 is bidirectional voice communication.

In the example depicted in FIG. 11, although a case is described inwhich the ProSe function 224 determines that the UEs 201, 202 are inproximity to each other, in some instances, the ProSe function 224 maydetermine that the UEs 201, 202 are not in proximity to each other. Insuch instances, the ProSe function 224 transmits via the MME 221 to theeNB 211, a page that includes a NACK (Negative ACKnowledgement)indicating that the UEs 201, 202 are not in proximity to each other. Inthis case, voice communication through a path passing through the eNB211 and the EPC 220 is performed between the UEs 201, 202.

Further, in the example depicted in FIG. 11, although a process isdescribed in which the ProSe function 224 transmits via the MME 221 tothe eNB 211, an ACK indicating that the UEs 201, 202 are in proximity toeach other, the process is not limited hereto. For example, the ProSefunction 224 may transmit directly to the eNB 211, a proximity alertindicating that the UEs 201, 202 are in proximity to each other. As aresult, the eNB 211 can be notified that the UEs 201, 202 are inproximity to each other and that shortcut communication through the basestation is possible between the UEs 201, 202.

FIG. 12 is a sequence diagram of a third example of processing in thewireless communications system. In FIG. 12, a case is described in whichthe UEs 201, 202 are connected to the eNBs 211, 212, respectively andvoice communication (telephone calling) between the UEs 201, 202 isperformed.

Steps S1201 to S1213 depicted in FIG. 12 are identical to steps S1101 toS1113 depicted in FIG. 11. However, at step S1201, the UE 202 performs aservice authorization process via the eNB 212. Further, steps S1205,S1207, and S1209 are performed via the eNB 212.

After step S1213, the ProSe function 224 transmits to the eNB 211, aproximity alert indicating that the UEs 201, 202 are in proximity toeach other (step S1214). The proximity alert includes identificationinformation of the UEs 201, 202. As a result, the eNB 211 can receivefrom the ProSe function 224, identifiers of the UEs 201, 202 andposition information related to the positions of the UEs 201, 202.

Further, the ProSe function 224 transmits to the MME 221, an ACKindicating that the UEs 201, 202 are in proximity to each other (stepS1215). The ACK transmitted at step S1215, for example, is received andprocessed by the MME 221 according to the NAS protocol.

Next, the MME 221 transmits to the eNB 212, a page that includes an ACKindicating that the UEs 201, 202 are in proximity to each other (stepS1216). The page transmitted at step S1216 includes identificationinformation of the UEs 201, 202. As a result, the eNB 212 is capable ofobtaining from the ProSe function 224, identifiers of the UEs 201, 202and position information related to the positions of the UEs 201, 202,via the MME 221.

Next, the eNB 212 transmits to the UE 202, the page transmitted at stepS1216 (step S1217) and thereby calls the UE 202. The operation at stepS1217 is performed by the eNB 212 and the UE 202 according to the S1AP.

Next, the UE 202 transmits to the MME 221, a NAS service requestrequesting voice communication with the UE 201 (step S1218). As aresult, for example, as depicted in FIG. 9B, communication through ashortcut path via the wireless base station starts between the UEs 201,202. However, in the example depicted in FIG. 12, since voicecommunication is performed between the UEs 201, 202, the communicationbetween the UEs 201, 202 is bidirectional voice communication. Further,in the example depicted in FIG. 12, since the UE 202 is connected to theeNB 212, communication between the UEs 201, 202 is communication via theeNBs 211, 212. The communication between the eNBs 211, 212 in this case,for example, is performed using an X2 interface.

In the example depicted in FIG. 12, although a case is described inwhich the ProSe function 224 determines that the UEs 201, 202 are inproximity to each other, in some instances, the ProSe function 224 maydetermine that the UEs 201, 202 are not in proximity to each other. Inthese instances, the ProSe function 224 transmits to the eNB 211, aproximity alert indicating that the UEs 201, 202 are not in proximity toeach other (NG). Further, the ProSe function 224 transmits to the eNB212 via the MME 221, a page that includes a NACK indicating that the UEs201, 202 are not in proximity to each other. In this case, voicecommunication through a path passing through the eNB 211 and the EPC 220is started between the UEs 201, 202.

Further, in the example depicted in FIG. 12, although a process isdescribed in which the ProSe function 224 transmits to the eNB 212 viathe MME 221, an ACK indicating that the UEs 201, 202 are in proximity toeach other, the process is not limited hereto. For example, the ProSefunction 224 may transmit directly to the eNB 212, a proximity alertindicating that the UEs 201, 202 are in proximity to each other. As aresult, the eNB 212 can be notified that the UEs 201, 202 are inproximity to each other and that shortcut communication through the basestation is possible between the UEs 201, 202.

FIG. 13 is a flowchart of an example of a process by the eNB. The eNB211, for example, executes the steps depicted in FIG. 13. Here, althougha process executed by the eNB 211 will be described, the eNBs 212, 213may also execute the same process as the eNB 211.

First, the eNB 211 receives from the ProSe function 224, positioninformation concerning the UEs 201, 202 (each UE) that are tocommunicate with each other (step S1301). The position information is,for example, a proximity alert, an ACK/NACK received via the MME 221, orthe like as described above.

Next, the eNB 211 determines whether the UEs 201, 202 are in proximityto each other based on the position information received at step S1301(step S1302). When determining that UEs 201, 202 are in proximity toeach other (step S1302: YES), the eNB 211 optimizes the route for thecommunication between the UEs 201, 202, by a path (the second path) thatdoes not pass through the EPC 220, (step S1303).

At step S1302, when determining that the UEs 201, 202 are not inproximity to each other (step S1302: NO), the eNB 211 transitions tostep S1304. In other words, the eNB 211 optimizes the route for thecommunication between the UEs 201, 202, by a path that passes throughthe EPC 220 (the first path) (step S1304).

Next, the eNB 211 relays the communication between the UEs 201, 202based on the result of the route optimization at step S1303 or stepS1304 (step S1305), and ends the series of operations.

In this manner, according to the second embodiment, the eNBs 211 to 213can implement the ProSe protocol and the eNBs 211 to 213 are capable ofusing the ProSe protocol to ascertain the proximity of UEs. As a result,eICBD (shortcut communication through the base station) can be executedbetween UEs that are in proximity to each other (for example, betweenthe UEs 201, 202). As a result, for example, communication in whichpackets do not pass through the EPC 220 is performed and a reduction oftraffic on the EPC 220 is possible.

As described, according to the wireless communications system, thecontrol station, and the terminal, traffic on a packet core network maybe alleviated.

However, to conventionally perform communications between terminals by ashortcut path through a base station, without passing through a packetcore network, determination of the physical proximity of the terminalshas to be performed at the base station. In the conventional techniqueabove, for example, when target terminals are connected to differentbase stations, determination of the physical proximity between theterminals is difficult to perform at the base stations and in someinstances, the amount of traffic on the packet core network may not bereduced.

According to one aspect of the present invention, an effect is achievedin that the amount of traffic in a packet core network can be reduced.

All examples and conditional language provided herein are intended forpedagogical purposes of aiding the reader in understanding the inventionand the concepts contributed by the inventor to further the art, and arenot to be construed as limitations to such specifically recited examplesand conditions, nor does the organization of such examples in thespecification relate to a showing of the superiority and inferiority ofthe invention. Although one or more embodiments of the present inventionhave been described in detail, it should be understood that the variouschanges, substitutions, and alterations could be made hereto withoutdeparting from the spirit and scope of the invention.

What is claimed is:
 1. A wireless communications system capable ofcommunications between terminals through a first path and communicationsbetween terminals through a second path that is different from the firstpath, the wireless communications system comprising: a plurality ofterminals; and a base station including: a memory; and a processorcoupled to the memory, the processor being configured to performprocessing related to proximity-based communications between theplurality of terminals, to obtain identifiers of the plurality ofterminals to control communication between the plurality of terminals tobe executed through the second path according to the identifiers andwhether an amount of delay of communication is less than a predeterminedamount, wherein the processor controls the communication to be executedthrough the second path when the amount of delay of communication isless than the predetermined amount.
 2. The wireless communicationssystem according to claim 1, wherein the base station receives by theprocessing related to the proximity-based communications, theidentifiers from a communications apparatus that provides theproximity-based communications.
 3. A base station of a wirelesscommunications system, the wireless communications system being capableof communications between terminals through a first path andcommunications between terminals through a second path that is differentfrom the first path, the base station comprising: a memory; and aprocessor coupled to the memory, the processor being configured toperform processing related to proximity-based communications between aplurality of terminals, and to obtain identifiers of the plurality ofterminals and to control communication between the plurality ofterminals to be executed through the second path according to theidentifiers and whether an amount of delay of communication is less thana predetermined amount, wherein the processor controls the communicationto be executed through the second path when the amount of delay ofcommunication is less than the predetermined amount.
 4. The base stationaccording to claim 3, wherein the processor receives, by the processingrelated to the proximity-based communications, the identifiers from acommunications apparatus that provides the proximity-basedcommunications.
 5. The base station according to claim 3, wherein thefirst path is included in a packet core network.
 6. The base stationaccording to claim 3, wherein the processor further obtains informationthat enables determination of whether to use the second path that isdifferent from the first path.
 7. The base station according to claim 6,wherein the processor causes the communication to be executed throughthe second path, according to the identifiers, the information, andwhether the amount of delay of communication is less than thepredetermined amount.
 8. The base station according to claim 3, whereinthe processor controls the communication to be executed through thefirst path when the amount of delay of communication is thepredetermined amount or more.
 9. A terminal of a wireless communicationssystem, the wireless communications system being capable ofcommunications between terminals through a first path and communicationsbetween terminals through a second path that is different from the firstpath, the terminal comprising: a memory; and a processor coupled to thememory, the processor being configured to: control communication with asecond terminal according to a control signal from a base station; andtransmit an identifier of the terminal to the base station, the terminalperforms proximity-based communications between the terminal and thesecond terminal, based upon identifiers of the terminal and the secondterminal, and whether an amount of delay of communication is less than apredetermined amount, wherein the communication to be executed throughthe second path when the amount of delay of communication is less thanthe predetermined amount.
 10. The terminal according to claim 9, whereinthe first path is included in a packet core network.
 11. The terminalaccording to claim 9, wherein the processor further transmitsinformation that enables determination of whether to use the second paththat is different from the first path.
 12. The terminal according toclaim 9, wherein the processor controls the communication to be executedthrough the first path when the amount of delay of communication is thepredetermined amount or more.